Expandable Interbody Spacers Implanted Through a Lateral Approach: A Multicenter Observational Study at Two Years

Introduction: Evidence surrounding use of expandable interbody devices during lateral lumbar interbody fusion (LLIF) has been sparse. While all LLIF devices purport to offer advantages such as avoidance of great vessels anteriorly and the spinal cord posteriorly, sufficient consensus among data for expandable devices is lacking, particularly among multiple surgeons who may have varied surgical correction goals with these devices. Objective: This study sought to describe outcomes of patients treated with expandable interbody spacers implanted through an LLIF approach. Methods: The current study’s patients were consecutively enrolled/ treated with one of two expandable interbody spacer designs by five surgeons at five sites, using a conventional transpsoas approach. Visual Analog Scale (VAS) back/leg pain scores, Oswestry Disability Index (ODI), and plain film radiographs were collected. Patients completed self-reported outcomes preoperatively and at 6, 12 weeks, 6, 12, and 24 months postoperative. Results: A total of 79 patients were enrolled across five study sites. Average age at time of surgery was 63 years (Range 33– 81). Average VAS lower back pain scores decreased significantly (p<0.001) from 6.7 (± 2.3) preoperatively to 2.9 (± 3.3) at 12 months and 2.9 (± 3.3) at 24 months. Average VAS leg pain scores decreased significantly (p<0.001) from 5.6 (± 2.8) preoperatively to 2.3 (± 2.6) at 12 months and 2.5 (± 2.9) at 24 months. Average ODI scores decreased significantly (p<0.001) from 45.9 (± 15.7) preoperatively to 25.0 (± 23.3) at 12 months and 26.2 (± 23.3) at 24 months. Disc height increased significantly (p<0.001) from 7.7 (± 2.6) preoperatively to 12.1 (± 2.8) at 12 months and 11.5 (± 2.4) at 24 months. There was no significant difference (p=0.091) in disc height between 12 and 24 months, suggesting a maintenance of disc height during this period. Conclusions: This multicenter, multi-surgeon study of two expandable lumbar interbody spacer designs demonstrates positive clinical and radiographic outcomes at 2 years.